[PATCH v4] doc: announce KNI deprecation

[Ferruh Yigit]

On 7/14/2022 3:50 PM, Ferruh Yigit wrote:
> On 7/14/2022 10:20 AM, Bruce Richardson wrote:
>> On Wed, Jul 13, 2022 at 06:10:47PM +0200, Thomas Monjalon wrote:
>>> From: Ferruh Yigit <ferruh.yigit at intel.com>
>>>
>>> Announce the deprecation plan for KNI kernel module, library and 
>>> example.
>>>
>>> Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
>>> Signed-off-by: Thomas Monjalon <thomas at monjalon.net>
>>> ---
>>> Squashed and updated 2 deprecations:
>>> https://patches.dpdk.org/project/dpdk/patch/20211124171609.3101896-2-ferruh.yigit@intel.com/
>>> https://patches.dpdk.org/project/dpdk/patch/20211124171609.3101896-2-ferruh.yigit@intel.com/
>>> ---
>>
>> One suggestion below.
>> With corrected link and with/without suggested change:
>>
>> Acked-by: Bruce Richardson <bruce.richardson at intel.com>
>>
>>>   doc/guides/prog_guide/kernel_nic_interface.rst | 3 +++
>>>   doc/guides/rel_notes/deprecation.rst           | 9 +++++++++
>>>   2 files changed, 12 insertions(+)
>>>
>>> diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst 
>>> b/doc/guides/prog_guide/kernel_nic_interface.rst
>>> index e021cc69b6..03b5bca958 100644
>>> --- a/doc/guides/prog_guide/kernel_nic_interface.rst
>>> +++ b/doc/guides/prog_guide/kernel_nic_interface.rst
>>> @@ -8,6 +8,9 @@ Kernel NIC Interface
>>>   .. note::
>>> +   KNI is deprecated and will be removed in future.
>>> +   See :doc:`../rel_notes/deprecation`.
>>> +
>>>      For an alternative to KNI, that does not require any out-of-tree 
>>> Linux kernel modules,
>>>      or a custom library, see :ref:`virtio_user_as_exception_path`.
>>> diff --git a/doc/guides/rel_notes/deprecation.rst 
>>> b/doc/guides/rel_notes/deprecation.rst
>>> index 4e5b23c53d..e54597c591 100644
>>> --- a/doc/guides/rel_notes/deprecation.rst
>>> +++ b/doc/guides/rel_notes/deprecation.rst
>>> @@ -48,6 +48,15 @@ Deprecation Notices
>>>     in the header will not be considered as ABI anymore. This change 
>>> is inspired
>>>     by the RFC 
>>> https://patchwork.dpdk.org/project/dpdk/list/?series=17176.
>>> +* kni: The KNI kernel module and library are not recommended for use 
>>> by new
>>> +  applications - other technologies such as virtio-user are 
>>> recommended instead.
>>> +  The KNI kernel module and library will be removed from DPDK 23.11,
>>> +  following the DPDK technical board
>>> +  `decision 
>>> <https://mails.dpdk.org/archives/dev/2021-January/197077.html>`_
>>> +  and `refinement 
>>> <http://mails.dpdk.org/archives/dev/2022-June/243596.html>`_.
>>> +  The first steps are to add deprecation warnings
>>> +  and to remove the example application from 22.11.
>>> +
>>
>> I wonder whether having this done as bullet points in chronological order
>> might be clearer. Something like:
>>
>> * kni: The KNI kernel module and library are not recommended for use 
>> by new
>>    applications - other technologies such as virtio-user are 
>> recommended instead.
>>    Following the DPDK technical board
>>    `decision 
>> <https://mails.dpdk.org/archives/dev/2021-January/197077.html>`_
>>    and `refinement 
>> <http://mails.dpdk.org/archives/dev/2022-June/243596.html>`_:
>>    * The KNI example application will be removed from DPDK 22.11 release
>>    * The KNI kernel module and library will be removed from the DPDK 
>> 23.11
>>      release
> 
> +1 to list actions in chronological order
> 
> I have a concern with removing sample application without replacing one 
> with alternate methods: virtio-user and tun/tap.
> 
> It is easy to create a virtio-user PMD by testpmd or any sample 
> application, and as far as I understand Bruce already documented this. 
> But for many KNI users they are not using KNI PMD, so replacing KNI with 
> this new method may require some hand holding.

As mentioned KNI PMD, it also should be removed when library and module 
are removed, may be good to list above to be explicit.

> One option can be hotplug the virtio-user PMD and use the port_id for 
> packet forwarding, and I don't know if the PMD has APIs that 
> applications can use directly, as done in KNI, @Maxime & @Chenbo can 
> answer this better.
> 
> It can be good to have a sample application for above before deprecating 
> the KNI sample application.
> And same sample can use tun/tap PMD with a runtime parameter, to show 
> how other example can be used, again tap can be used as tap PMD or Linux 
> tun/tap APIs.
> 
> Question is who can work on such a sample, but if we can find some 
> resource I am for having a replacement exception path sample app before 
> deprecating KNI.
> 
> Thanks,
> ferruh
> 
> 
>